Thermoplastic compositions for halogenated elastomers

ABSTRACT

The invention provides a thermoplastic composition of C 4 -C 7  isoolefin copolymers including halomethylstyrene derived units blended with a hindered amine or phosphine of the structure R 1  R 2  R 3  N or R 1  R 2  R 3  P wherein R 1 , R 2  and R 3  are preferably lower and higher alkyl groups. The resulting ionically associated, amino or phosphine modified elastomers are used to prepare thermoplastic elastomer blend compositions, including dynamically vulcanized compositions, containing more finely dispersed elastomers which results in compositions having improved mechanical properties.

FIELD OF THE INVENTION

[0001] The present invention relates to halogenated elastomers havingenhanced viscosity and thermoplastic elastomer composition containingthese elastomers. These thermoplastic elastomeric compositions compriseblends of an isoolefin copolymer comprising at least a halomethylstyrenederived unit and at least one amine or phosphine.

BACKGROUND

[0002] A thermoplastic elastomer is generally defined as a polymer orblend of polymers that can be processed and recycled in the same way asa conventional thermoplastic materials, yet has properties andperformance similar to that of vulcanized rubber at servicetemperatures. Blends or alloys of plastic and elastomeric rubber havebecome increasingly important in the production of high performancethermoplastic elastomers, particularly for the replacement of thermosetrubber in various applications.

[0003] Polymer blends which have a combination of both thermoplastic andelastic properties are generally obtained by combining a thermoplasticpolymer with an elastomeric composition in a way such that the elastomeris intimately and uniformly dispersed as a discrete particulate phasewithin a continuous phase of the thermoplastic. Early work withvulcanized compositions is found in U.S. Pat. No. 3,037,954 whichdiscloses static vulcanization as well as the technique of dynamicvulcanization wherein a vulcanizable elastomer is dispersed into aresinous thermoplastic polymer and the elastomer is cured whilecontinuously mixing and shearing the polymer blend. The resultingcomposition is a microgel dispersion of cured elastomer, such as butylrubber, chlorinated butyl rubber, polybutadiene or polyisoprene in anuncured matrix of thermoplastic polymer such as polypropylene.

[0004] Depending on the ultimate application, such thermoplasticelastomer (TPE) compositions may comprise one or a mixture ofthermoplastic materials such as propylene homopolymers and propylenecopolymers and like thermoplastics used in combination with one or amixture of cured or non-cured elastomers such as ethylene/propylenerubber, EPDM rubber, diolefin rubber, butyl rubber or similarelastomers. TPE compositions may also be prepared where thethermoplastic material used is an engineering resin having good hightemperature properties, such as a polyamide or a polyester, used incombination with a cured or non-cured elastomer. Examples of such TPEcompositions and methods of processing such compositions, includingmethods of dynamic vulcanization, may be found in U.S. Pat. Nos.4,130,534, 4,130,535, 4,594,390, 5,021,500, 5,177,147 and 5,290,886, aswell as in WO 92/02582.

[0005] Particularly preferred elastomeric polymers useful for preparingTPE compositions are halogenated random isoolefin copolymers comprisingat least halomethylstyrene derived units. Halogenated elastomericcopolymers of this type (referred to as BIMS polymers) and their methodof preparation are disclosed in U.S. Pat. No. 5,162,445. Curable TPEcompositions containing these copolymers are described in U.S. Pat. Nos.5,013,793 and 5,051,477, among others.

[0006] TPE compositions are normally prepared by melt mixing or meltprocessing the thermoplastic and elastomeric components at temperaturesin excess of 150° C. and under high shear mixing conditions (shear rategreater than 100 1/sec or sec⁻¹) in order to achieve a fine dispersionof one polymer system within a matrix of the other polymer system. Thefiner the dispersion, the better are the mechanical properties of theTPE product.

[0007] Due to the flow activation and shear thinning characteristicinherent in such BIMS polymers, reductions in viscosity values of thesepolymers at increased temperatures and shear rates encountered duringmixing are much more pronounced than reductions in viscosity of thethermoplastic component with which the BIMS polymer is blended. However,minimization of the viscosity differential between the BIMS andthermoplastic components during mixing and/or processing is essentialfor the provision of uniform mixing and fine blend morphology that arecritical for good blend mechanical properties.

SUMMARY OF THE INVENTION

[0008] The invention provides a composition, preferably a thermoplasticcomposition, comprising a halogenated elastomer and a viscosityenhancing agent such as a hindered amine or phosphine. In one embodimentof the invention, the halogenated elastomer is a C₄ to C₇ isomonoolefincopolymer comprising halomethylstyrene derived units. The copolymer ismixed with at least one hindered amine or phosphine compound having therespective structure (R₁ R₂ R₃)N or (R₁ R₂ R₃)P wherein R₁ is H or C₁ toC₆ alkyl, R₂ is C₁ to C₃₀alkyl and R₃ is C₄ to C₃₀ alkyl and furtherwherein R₃ is a higher alkyl than R₁, said mixing being accomplished ata temperature above the melting point of said hindered amine orphosphine compound. The mixing is preferably done in such a manner tocreate a homogeneous blend.

[0009] The invention further provides a process for increasing theviscosity of a C₄ to C₇ isomonoolefin copolymer comprising mixing thecopolymer with a hindered amine or phosphine compound.

[0010] The invention provides a new approach towards viscosityenhancement of BIMS copolymers such that their viscosity during highshear thermal mixing more closely approaches or matches the viscosity ofthermoplastic materials with which they are blended, therebyfacilitating more uniform mixing and the development of a finerdispersion of one polymer system within the other matrix polymer system.

DETAILED DESCRIPTION

[0011] As used herein, the term “dynamic vulcanization” means avulcanization or curing process for a rubber contained in athermoplastic elastomer composition, wherein the rubber is vulcanizedunder conditions of high shear at a temperature above the melting pointof the component thermoplastic. The rubber is thus simultaneouslycrosslinked and dispersed as fine particles within the thermoplasticmatrix, although as noted above other morphologies may also exist.

[0012] As used herein, the term “vulcanized” means that the rubbercomponent to be vulcanized has been cured to a state in which theelastomeric properties of the crosslinked rubber are similar to those ofthe rubber in its conventional vulcanized state, apart from thethermoplastic elastomer composition. The degree of cure can be describedin terms of gel content or, conversely, extractable components.Alternatively the degree of cure may be expressed in terms of crosslinkdensity. All of these descriptions are well known in the art, forexample in U.S. Pat. Nos. 5,100,947 and 5,157,081.

[0013] As used herein, the term “composition” includes blends of thehalogenation product of random copolymers of a C₄ to C₇ isomonoolefin,such as isobutylene, and an alkylstyrene comonomer, and the agent usedto influence the viscosity, such as an amine or phosphine. Thecomposition may also include other components.

[0014] As used herein, in reference to Periodic Table “Groups”, the newnumbering scheme for the Periodic Table Groups are used as in HAWLEY'SCONDENSED CHEMICAL DICTIONARY 852 (13th ed. 1997).

[0015] The term “elastomer”, as used herein, refers to any polymer orcomposition of polymers consistent with the ASTM D1566 definition. Theterm “elastomer” may be used interchangeably with the term “rubber”, asused herein.

[0016] Isoolefin copolymer comprising a halomethylstyrene derived unit

[0017] Compositions of the present invention include at least onehalogenated elastomer. The halogenated elastomer in one embodiment ofthe invention is a random copolymer of comprising at least C₄ to C₇isoolefin derived units, such as isobutylene derived units, andhalomethylstyrene derived units. The halomethylstyrene unit may be anortho-, meta-, or para-alkyl-substituted styrene unit. In oneembodiment, the halomethylstyrene derived unit is a p-halomethylstyrenecontaining at least 80%, more preferably at least 90% by weight of thepara-isomer. The “halo” group can be any halogen, desirably chlorine orbromine. The halogenated elastomer may also include functionalizedinterpolymers wherein at least some of the alkyl substituents groupspresent in the styrene monomer units contain benzylic halogen or someother functional group described further below. These interpolymers areherein referred to as “isoolefin copolymers comprising ahalomethylstyrene derived unit” or simply “isoolefin copolymer”.

[0018] The isoolefin copolymer may also include other monomer derivedunits. The isoolefin of the copolymer may be a C₄ to C₁₂ compound,non-limiting examples of which are compounds such as isobutylene,isobutene, 2-methyl-1-butene, 3-methyl-1-butene, 2-methyl-2-butene,1-butene, 2-butene, methyl vinyl ether, indene, vinyltrimethylsilane,hexene, and 4-methyl-1-pentene. The copolymer may also further comprisemultiolefin derived units. The multiolefin is a C₄ to C₁₄ multiolefinsuch as isoprene, butadiene, 2,3-dimethyl-1,3-butadiene, myrcene,6,6-dimethyl-fulvene, hexadiene, cyclopentadiene, and piperylene, andother monomers such as disclosed in EP 0 279 456 and U.S. Pat. Nos.5,506,316 and 5,162,425. Desirable styrenic monomer derived units thatmay comprise the copolymer include styrene, methylstyrene,chlorostyrene, methoxystyrene, indene and indene derivatives, andcombinations thereof.

[0019] In another embodiment of the invention, the interpolymer is arandom elastomeric copolymer of an ethylene derived unit or a C₃ to C₆α-olefin derived unit and an halomethylstyrene derived unit, preferablyp-halomethylstyrene containing at least 80%, more preferably at least90% by weight of the para-isomer and also include functionalizedinterpolymers wherein at least some of the alkyl substituents groupspresent in the styrene monomer units contain benzylic halogen or someother functional group.

[0020] Preferred isoolefin copolymers may be characterized asinterpolymers containing the following monomer units randomly spacedalong the polymer chain:

[0021] wherein R and R¹ are independently hydrogen, lower alkyl,preferably C₁ to C₇ alkyl and primary or secondary alkyl halides and Xis a functional group such as halogen. Desirable halogens are chlorine,bromine or combinations thereof. Preferably R and R¹ are each hydrogen.The —CRR₁H and —CRR₁X groups can be substituted on the styrene ring ineither the ortho, meta, or para positions, preferably para. Up to 60mole % of the p-substituted styrene present in the interpolymerstructure may be the functionalized structure (2) above in oneembodiment, and in another embodiment from 0.1 to 5 mol %. In yetanother embodiment, the amount of functionalized structure (2) is from0.4 to 1 mol %.

[0022] The functional group X may be halogen or some other functionalgroup which may be incorporated by nucleophilic substitution of benzylichalogen with other groups such as carboxylic acids; carboxy salts;carboxy esters, amides and imides; hydroxy; alkoxide; phenoxide;thiolate; thioether; xanthate; cyanide; cyanate; amino and mixturesthereof. These functionalized isomonoolefin copolymers, their method ofpreparation, methods of functionalization, and cure are moreparticularly disclosed in U.S. Pat. No. 5,162,445.

[0023] Most useful of such functionalized materials are elastomericrandom interpolymers of isobutylene and p-methylstyrene containing from0.5 to 20 mole % p-methylstyrene wherein up to 60 mole % of the methylsubstituent groups present on the benzyl ring contain a bromine orchlorine atom, preferably a bromine atom (p-bromomethylstyrene), as wellas acid or ester functionalized versions thereof wherein the halogenatom has been displaced by maleic anhydride or by acrylic or methacrylicacid functionality. These interpolymers are termed “halogenatedpoly(isobutylene-co-p-methylstyrene)” or “brominatedpoly(isobutylene-co-p-methylstyrene)”, and are commercially availableunder the name EXXPRO™ Elastomers (ExxonMobil Chemical Company, HoustonTex.). It is understood that the use of the terms “halogenated” or“brominated” are not limited to the method of halogenation of thecopolymer, but merely descriptive of the copolymer which comprises theisobutylene derived units, the p-methylstyrene derived units, and thep-halomethylstyrene derived units.

[0024] These functionalized polymers preferably have a substantiallyhomogeneous compositional distribution such that at least 95% by weightof the polymer has a p-alkylstyrene content within 10% of the averagep-alkylstyrene content of the polymer. More preferred polymers are alsocharacterized by a narrow molecular weight distribution (Mw/Mn) of lessthan 5, more preferably less than 2.5, a preferred viscosity averagemolecular weight in the range of from 200,000 up to 2,000,000 and apreferred number average molecular weight in the range of from 25,000 to750,000 as determined by gel permeation chromatography.

[0025] The copolymers may be prepared by a slurry polymerization of themonomer mixture using a Lewis acid catalyst, followed by halogenation,preferably bromination, in solution in the presence of halogen and aradical initiator such as heat and/or light and/or a chemical initiatorand, optionally, followed by electrophilic substitution of bromine witha different functional derived unit.

[0026] Preferred halogenated poly(isobutylene-co-p-methylstyrene) arebrominated polymers which generally contain from 0.1 to 5 wt % ofbromomethyl groups. In yet another embodiment, the amount of bromomethylgroups is from 0.2 to 2.5 wt %. Expressed another way, preferredcopolymers contain from 0.05 up to 2.5 mole % of bromine, based on theweight of the polymer, more preferably from 0.1 to 1.25 mole % bromine,and are substantially free of ring halogen or halogen in the polymerbackbone chain. In one embodiment of the invention, the interpolymer isa copolymer of C₄ to C₇ isomonoolefin derived units, a p-methylstyrenederived units and a p-halomethylstyrene derived units, wherein thep-halomethylstyrene units are present in the interpolymer from 0.4 to 1mol % based on the interpolymer. In another embodiment, thep-halomethylstyrene is p-bromomethylstyrene. The Mooney Viscosity (1+8,125° C., ASTM D1646, modified) is from 30 to 60 MU.

[0027] Amine/phosphine Component

[0028] Viscosity enhancement of the BIMS copolymers is achieved bymixing the BIMS copolymer with the appropriate hindered amine orphosphine compounds (or “viscosity enhancers”) under conditions of shearand at temperatures above the melting point of the amine or phosphinefor a period of time sufficient to allow the amine or phosphine tobecome uniformly dispersed within the BIMS material, usually 1 to 10minutes and at preferred temperatures in the range of 100 to 180° C.

[0029] Suitable preferred viscosity enhancers which may be used includethose described by the formula (R₁ R₂ R₃)Q, wherein Q is a Group 15element, preferably nitrogen or phosphorous, and wherein R₃ is a C₁₀ toC₂₀ alkyl and R₁ and R₂ are the same or different lower alkyls, morepreferably C₁ to C₆ alkyls. Preferred are hindered amine/phosphinecompounds which may be used include those tertiary amines of the aboveformula (R₁ R₂ R₃)N. Especially preferred amines are decyldimethylamine, hexadecyldimethylamine, hydrogenated tallowalkyl dimethyamine,dihydrogenated tallowalkylmethyl amine and like compounds.

[0030] Preferred hindered phosphine compounds of the formula (R₁ R₂ R₃)Pare also those wherein R₃ is C₁₀ to C₂₀ alkyl and R₁ and R₂ are the sameor different lower alkyls, more preferably C₁ to C₆ alkyls. Thesephosphines are analogous to the amines listed above.

[0031] The quantity of amine or phosphine incorporated into the BIMScopolymer should be sufficient such that the viscosity of thecomposition is enhanced (increased at a given shear rate andtemperature). The resultant composition may be referred to variously asthe “amine or phosphine/copolymer” composition, or the “viscosityenhancer/copolymer” composition, or the “amine or phosphine/BIMS”composition. In one embodiment, the viscosity value of the viscosityenhancer/BIMS composition is greater than 1300 at 220° C. and 100 1/sshear rate, and in another embodiment the value is from 1300 to 6000Pa·s at 220° C. and 100 1/s shear rate, and from 1400 to 5000 Pa·s at220° C. and 100 1/s shear rate in another embodiment. In anotherembodiment, the viscosity value of the viscosity enhancer/BIMScomposition is greater than 200 at 220° C. and 1000 1/s shear rate, andin another embodiment the value is from 200 to 600 Pa·s at 220° C. and1000 1/s shear rate, and from 220 to 550 Pa·s at 220° C. and 1000 1/sshear rate in another embodiment. Generally, from 0.05 to 2 moleequivalents, more preferably from 0.1 to 1 mole equivalents, of amine orphosphine per halogen of BIMS is sufficient.

[0032] The viscosity enhancer/BIMS composition, an amine/BIMS in oneembodiment, of the present invention is produced substantially in theabsence of a solvent. More particularly, the amine and BIMS componentsare blended by techniques known to those skilled in the art without theaddition of an organic solvent. Solvents, especially organic solvents,are substantially absent in the composition, or during blending of thecomponents. By “substantially absent”, it is meant that there is lessthan 5 wt % solvent by weight of the entire composition present, andless than 2 wt % in another embodiment.

[0033] The modified BIMS polymers of this invention are to bedistinguished from the ionomers disclosed in U.S. Pat. No. 5,162,445 orWO9410214. The materials produced in these references involvenucleophilic substitution reactions conducted in organic solvent whereinbenzylic halogen present in the BIMS polymer is displaced therebyconverting the polymer to an ionomer with ionic amine or phosphinefunctionality. Materials produced in accordance with this invention arebelieved to be ionically associated polymer chains with no halogendisplacement in the polymer chains. This ionic association provides amodified polymer having increased viscosity as compared with thestarting BIMS polymer.

[0034] Thermoplastic Polymers

[0035] The enhanced viscosity isoolefin copolymer of the invention isuseful in blending with thermoplastics. Thermoplastic polymers suitablefor use in the present invention include amorphous, partiallycrystalline or essentially totally crystalline polymers selected frompolyolefins, polyamides, polyimides, polyesters, polycarbonates,polysulfones, polylactones, polyacetals, acrylonitrile/butadiene/styrenecopolymer resins, polyphenylene oxides, ethylene-carbon monoxidecopolymers, polyphenylene sulfides, polystyrene, styrene/acrylonitrilecopolymer resins, styrene/maleic anhydride copolymer resins, aromaticpolyketones and mixtures thereof. These and other thermoplastics aredisclosed in, for example, U.S. Pat. No. 6,013,727.

[0036] Polyolefins suitable for use in the compositions of the inventioninclude thermoplastic, at least partially crystalline polyolefinhomopolymers and copolymers, including polymers prepared usingZiegler/Natta type catalysts or single sight catalysts such asmetallocene catalysts. They are desirably prepared from monoolefinmonomers having 2 to 6 carbon atoms, such as ethylene, propylene,1-butene, isobutylene, 1-pentene, copolymers containing these monomers,and the like, with propylene being the preferred monomer. As used in thespecification and claims, the term polypropylene includes homopolymersof propylene as well as reactor copolymers of propylene which cancontain 1 to 20 wt % of ethylene or an alpha-olefin comonomer of 4 to 16carbon atoms or mixtures thereof. The polypropylene can be highlycrystalline isotactic or syndiotactic polypropylene, usually having anarrow range of glass transition temperature (Tg). Commerciallyavailable polyolefins may be used in the practice of the invention.

[0037] The term “polypropylene” includes homopolymers of propylene aswell as reactor copolymer of polypropylene which can contain from 1 to20 wt % ethylene derived units or other 4 to 6 carbon α-olefin comonomerderived units. The polypropylene can be highly crystalline isotactic orsyndiotactic polypropylene. The reactor copolymer can be either randomor block copolymer. Other suitable thermoplastic polyolefin resinsinclude high density polyethylene (HDPE), low density polyethylene(LDPE), linear low density polyethylene (LLDPE), very low densitypolyethylene (VLDPE), ethylene copolymer resins, plastomeric copolymersof ethylene and 1-alkene, polybutene, and their mixtures.

[0038] Suitable thermoplastic polyamides (nylons) comprise crystallineor resinous, high molecular weight solid polymers including copolymersand terpolymers having recurring amide units within the polymer chain.Polyamides may be prepared by polymerization of one or more epsilonlactams such as caprolactam, pyrrolidinone, lauryllactam andaminoundecanoic lactam, or amino acid, or by condensation of dibasicacids and diamines. Both fiber-forming and molding grade nylons aresuitable. Examples of such polyamides are polycaprolactam (nylon-6),polylauryllactam (nylon- 12), polyhexamethyleneadipamide (nylon-6,6),polyhexamethyleneazelamide (nylon-6,9), polyhexamethylenesebacamide(nylon-6,10), polyhexamethyleneisophthalamide (nylon-6,IP) and thecondensation product of 11-amino-undecanoic acid (nylon-11).Commercially available thermoplastic polyamides may be advantageouslyused in the practice of this invention, with linear crystallinepolyamides having a softening point or melting point between 160°C.-230° C. being preferred.

[0039] Suitable thermoplastic polyesters which may be employed includethe polymer reaction products of one or a mixture of aliphatic oraromatic polycarboxylic acids esters of anhydrides and one or a mixtureof diols. Examples of satisfactory polyesters includepoly(trans-1,4-cyclohexylene), poly(C₂ to C₆ alkane biscarboxylates)such as poly(trans-1,4-cyclohexylene succinate) andpoly(trans-1,4-cyclohexylene adipate); poly(cis- ortrans-1,4-cyclohexanedimethylene) alkanedicarboxylates such aspoly(cis-1,4-cyclohexane-di-methylene) oxlate andpoly(cis-1,4-cyclohexane-di-methylene) succinate, poly(C₂ to C₄ alkyleneterephthalates) such as polyethylene terephthalate andpolytetramethylene-terephthalate, poly(C₂ to C₄ alkylene isophthalates)such as polyethyleneisophthalate and polytetramethylene-isophthalate andlike materials. Preferred polyester are derived from aromaticdicarboxylic acids such as naphthalenic or ophthalmic acids and C₂ to C₄diols, such as polyethylene terephthalate and polybutyleneterephthalate. Preferred polyesters will have a melting point in therange of 160° C. to 260° C.

[0040] Poly(phenylene ether) (PPE) thermoplastic engineering resinswhich may be used in accordance with this invention are well known,commercially available materials produced by the oxidative couplingpolymerization of alkyl substituted phenols. They are generally linearpolymers having a glass transition temperature in the range of 190° C.to 235° C. Examples of preferred PPE polymers includepoly(2,6-dialkyl-1,4-phenylene ethers) such aspoly(2,6-dimethyl-1,4-phenylene ether),poly(2-methyl-6-ethyl-1,4-phenylene ether),poly(2,6-dipropyl-1,4-phenylene ether) andpoly(2-ethyl-6-propyl-1,4-phenylene ether). These polymers, their methodof preparation and blends with polystyrene are further described in U.S.Pat. No. 3,383,435.

[0041] Other thermoplastic resins which may be used include thepolycarbonate analogs of the polyesters described above such assegmented poly(ether co-phthalates); polycaprolactone polymers; styreneresins such as copolymers of styrene with less than 50 mole % ofacrylonitrile (SAN) and resinous copolymers of styrene, acrylonitrileand butadiene (ABS); sulfone polymers such as polyphenyl sulfone andlike engineering resins as are known in the art.

[0042] Additives

[0043] The compositions of the invention may include plasticizers,curatives and may also include reinforcing and non-reinforcing fillers,antioxidants, stabilizers, rubber processing oil, plasticizers, extenderoils, lubricants, antiblocking agents, anti-static agents, waxes,foaming agents, pigments, flame retardants and other processing aidsknown in the rubber compounding art. Such additives can comprise up to50 wt % of the total composition. Fillers and extenders which can beutilized include conventional inorganics such as calcium carbonate,clays, silica, talc, titanium dioxide, carbon black and the like. Therubber processing oils generally are paraffinic, naphthenic or aromaticoils derived from petroleum fractions, but are preferably paraffinic.The type will be that ordinarily used in conjunction with the specificrubber or rubbers present in the composition, and the quantity based onthe total rubber content may range from zero up to 1-200 parts by weightper hundred rubber (phr). Plasticizers such as trimellitate esters mayalso be present in the composition.

[0044] Moreover, various phenolic resins known to the art and to theliterature can be utilized, as well as various phenol-formaldehyderesins as set forth in “The Chemistry of Phenol-Formaldehyde ResinVulcanization of EPDM: Part I. Evidence for Methylene Crosslinks,” byMartin Van Duin and Aniko Souphanthong, 68 RUBBER CHEMISTRY ANDTECHNOLOGY 717-727 (1995).

[0045] The cure agent of the present invention may include any number ofcomponents such as a metal or metal ligand complex, accelerators, resinsor other components known in the art to affect a cure of an elastomer.In its broadest embodiment, the cure agent is at least a Group 2-14metal oxide or metal ligand complex, wherein at least one ligand is ableto undergo a substitution reaction with the inducer compound. In oneembodiment, the at least one cure agent is a metal oxide which includeszinc oxide, hydrated lime, magnesium oxide, alkali carbonates, andhydroxides. In particular, the following metal-based cure agents arecommon curatives that will function in the present invention: ZnO, CaO,MgO, Al₂O₃, CrO₃, FeO, Fe₂O₃, and NiO, and/or carboxylates of thesemetals. These metal oxides can be used in conjunction with thecorresponding metal carboxylate complex, or with the carboxylate ligand,and either a sulfur compound or an alkylperoxide compound. (See also,Formulation Design and Curing Characteristics of NBR Mixes for Seals,RUBBER WORLD 25-30 (1993).

[0046] These metal oxides can be used in combination with anothercompound such as a fatty acid, and the cure agent is not herein limitedto the metal oxide or metal ligand complex alone. Examples of organic orfatty acids that can be used in the invention are stearic, oleic,lauric, palmitic, myristic acids, and mixtures thereof, and hydrogenatedoils from palm, castor, fish, and linseed oils. The use of these cureagents is discussed in RUBBER TECHNOLOGY 20-58 (Maurice Mortin, ed.,Chapman & Hall 1995), and in Rubber World Magazine's BLUE BOOK 2001109-137 (Don R. Smith, ed., Lippincott & Peto, Inc. 2001); and U.S. Pat.No. 5,332,787.

[0047] The amount of the curing agent will generally vary depending uponthe type utilized and especially the desired degree of cure, as is wellrecognized in the art. For example, the amount of sulfur is generallyfrom 1 to 5, and preferably from 2 to 3 parts by weight per 100 parts byweight of the composition. The amount of the peroxide curing agent isgenerally from 0.1 to 2.0 parts by weight, the amount of the phenoliccuring resin is generally from 2 to 10 parts by weight, and the amountof the hindered amine is from 0.1 to 2 parts by weight, all based upon100 parts by weight of the composition.

[0048] In one embodiment of the invention, curatives may be present from0.5 to 20 phr of the composition, and from 1 to 10 phr in anotherembodiment. In another embodiment, curatives are substantially absentfrom the composition. By “substantially absent”, it is meant thattraditional curatives such as phenolic resins, sulfur, peroxides, metalsand metal oxides, and metal-ligand complexes are not present in thecomposition.

[0049] Processing

[0050] The BIMS component of the thermoplastic elastomer is generallypresent as small, i.e., micro-size, particles within a continuousplastic matrix, although a co-continuous morphology or a phase inversionis also possible depending on the amount of rubber relative to plastic,and the cure system or degree of cure of the rubber. The rubber isdesirably at least partially crosslinked, and preferably is completelyor fully cross-linked in the final vulcanized thermoplastic composition.The partial or complete crosslinking can be achieved by adding anappropriate rubber curative to the blend of thermoplastic polymer andrubber and vulcanizing the rubber to the desired degree underconventional vulcanizing conditions. However, it is preferred that therubber be crosslinked by the process of dynamic vulcanization.

[0051] Dynamic vulcanization is effected by mixing the thermoplasticelastomer components at elevated temperature in conventional mixingequipment such as roll mills, Banbury™ mixers, Brabender™ mixers,continuous mixers, mixing extruders and the like. The uniquecharacteristic of dynamically cured compositions is that,notwithstanding the fact that the rubber component is partially or fullycured, the compositions can be processed and reprocessed by conventionalplastic processing techniques such as extrusion, injection molding, blowmolding and compression molding. Scrap or flashing can be salvaged andreprocessed.

[0052] Those ordinarily skilled in the art will appreciate theappropriate quantities, types of cure systems and vulcanizationconditions required to carry out the vulcanization of the BIMS rubber.The rubber can be vulcanized using varying amounts of curative, varyingtemperatures and varying time of cure in order to obtain the optimumcrosslinking desired. Any known cure system for the rubber can be used,so long as it is suitable under the vulcanization conditions with thespecific BIMS rubber being used and with the thermoplastic component.These curatives include sulfur, sulfur donors, metal oxides, resinsystems, peroxide-based systems, hydrosilation curatives, containingplatinum or peroxide catalysts, and the like, both with and withoutaccelerators and co-agents. Such cure systems are well known in the artand literature of vulcanization of elastomers.

[0053] Depending upon the desired applications, the amount of rubberpresent in the composition may range from 10 to 90 wt % of the totalpolymer content of the composition. In most applications andparticularly where the rubber component is dynamically vulcanized, therubber component will constitute less than 70 wt %, more preferably lessthan 50 wt %, and most preferably 10-40 wt % of the total polymercontent of the composition.

[0054] Melt processing temperatures of the TPE compositions willgenerally range from above the melting point of the highest meltingpolymer present in the TPE composition up to 300° C. Preferredprocessing temperatures will range from 140° C. up to 260° C., from 150°C. up to 240° C. in another embodiment, and from 170° C. to 220° C. inyet another embodiment.

[0055] The hindered amine or phosphine compound may be combined with theBIMS rubber component at any mixing stage, i.e., when the BIMS andthermoplastic polymer are initially mixed or at the time that curativesor other additives are mixed where dynamically vulcanized compositionsare prepared. However, in a preferred embodiment, the hindered amine orphosphine material is fist compounded the BIMS polymer at temperaturesup to 300° C. to provide a modified BIMS polymer of increased viscosity,and this modified polymer then blended with the thermoplastic resin andany other additives present in the TPE composition.

[0056] The thermoplastic composition of the invention results from themixing of the amine or phosphine, the isoolefin copolymer, and thethermoplastic, in any order. In one embodiment, the copolymer is firstmixed with the amine or phosphine to form an amine orphosphine/copolymer composition, followed by mixing with thethermoplastic. In another embodiment, the three components are mixedsimultaneously. Further, the thermoplastic composition in one embodimentof the present invention is produced substantially in the absence of asolvent. More particularly, the amine and BIMS components are blended bytechniques known to those skilled in the art without the addition of anorganic solvent. Further, the amine or phosphine/copolymer compositionthus formed may be mixed with the thermoplastic in the absence of asolvent. Solvents, especially organic solvents such as hexane, methylenechloride and other solvents known to dissolve polyolefins, nylons andhalogenated elastomers, are substantially absent in the composition, orduring blending of the components. By “substantially absent”, it ismeant that there is less than 5 wt % solvent by weight of the entirecomposition present.

[0057] The thermoplastic compositions of the invention may comprise from10 to 90 wt % of the thermoplastic and from 90 to 10 wt % of theisoolefin copolymer. In another embodiment, the thermoplasticcompositions of the invention may comprise from 20 to 80 wt % of thethermoplastic and from 80 to 20 wt % of the isoolefin copolymer. Inanother embodiment, the thermoplastic compositions of the inventioncomprise from 40 to 60 wt % of the thermoplastic, and from 60 to 40 wt %of the isoolefin copolymer. The vulcanized thermoplastic compositionshave a tensile toughness of greater than 1000 psi in one embodiment, andgreater than 2000 psi in another embodiment (ASTM D1708 as in textbelow). The vulcanized thermoplastic compositions have a strain at breakvalue of greater than 200% in one embodiment, and greater than 300% inanother embodiment (ASTM D1708 as in text below).

EXAMPLES

[0058] The following examples are illustrative of the invention.Materials used in the examples are shown in Table 1.

Example 1

[0059] This example illustrates the breakdown in viscosity of brominatedpoly(isobutylene-co-p-methylstyrene) (identified as BIMS 1, 2 and 3 inTable 1). Samples of each rubber were subjected to shear rates from 50to 5,000 s⁻¹ using a capillary rheometer at a temperature of 220° C.Viscosity data were subsequently corrected for entry pressure andnon-Newtonian flow profile. Only viscosity values at 100, 500, 1000 and1500 s⁻¹ are shown for comparison. Table 2 shows the drop off ofviscosity as a function of increased rate of shear for each of theserubbers.

Example 2

[0060] All tertiary amines, DM16D, DMHTD and M2HT, were blended intoBIMS 2 by a Brabender™ mixer running at 150° C. and at 60 rpm. Amineamounts were added in mole equivalents to the bromine content in BIMS.As shown in Table 3, by adding DM16D, viscosity values at all shearrates of BIMS at 220° C. could be raised.

[0061] The presence of tertiary amine of DM16D in BIMS does not lead toany thermal degradation in BIMS as demonstrated in Table 4. Viscosityvalues of DM16D-added BIMS at each temperature remain relativelyunchanged during thermal cycling between 100 and 250° C.

[0062] The enhancement in viscosity value in tertiary-amine modifiedBIMS depends on the amine structure. By comparing the data in Table 5with Table 3, hexadecyl-dimethylamine of DM16D provides more enhancementin viscosity as compared with that of DMHTD, which is dimethyl but withpredominately C₁₈ R₃ group as compared with the C₁₆ R₃ group for DM16D.When M2HT, which is dihydrogenated tallowalkyl-methylamine and has bothR₂ and R₃ groups as the alkyl group with predominantly C₁₈, is applied(see Table 6), the viscosity enhancement becomes less significant ascompared with that provided by adding DM16D.

Example 3

[0063] A blend comprising 60 wt % of MFR 1.5 polypropylene (ExxonMobilPP4292) and 40 wt % of BIMS 2 modified with 0.5 mol equivalents of DM16Dwas prepared by mixing the components using a Brabender™ mixer at 80 RPMand 220° C. for a period of 5 minutes.

[0064] An otherwise identical control blend was prepared except the BIMS2 was not amine modified (control). Morphologies of the resulting blendswere examined by AFM (Atomic Force Microscopy) followed by imageprocessing to determine dispersion sizes in terms of number averageequivalent diameter. All specimens were analyzed within 8 hours aftercryofacing to prevent specimen relaxation. During cryofacing, thespecimens were cooled to −150° C. and cut with diamond knives in aReichert cryogenic microtome. They were then stored in a dissector underflowing dry nitrogen gas to warm up to ambient temperatures withoutcondensation being formed. Finally, the faced specimens were mounted ina miniature steel vice for AFM analysis. The AFM measurements wereperformed in air on a NanoScope Dimension 3000 scanning probe microscope(Digital Instrument) using a rectangular Si cantilever. AFM phase imagesof all specimens were converted into a TIFF format and processed usingPHOTOSHOP™ (Adobe Systems, Inc.). The image processing tool kit(Reindeer Games, Inc.) was applied for image measurements. Results ofimage measurements were written into a text file for subsequent dataprocessing using EXCEL™. Results are shown in Table 7. These resultsdemonstrate a nearly 30% reduction in size of the dispersed BIMS rubbercompared with the control.

[0065] In the following examples, additional thermoplastic blends, orionically linked alloy (ILA) compositions were prepared containingvarying levels of tertiary amine and their mechanical properties wereevaluated vs. control samples which contain no tertiary amine additive.The thermoplastic polymer used in these blends is polypropylene (PP)PP4722, a 2.8 MFR polypropylene available from ExxonMobil Chemical Co.

Example 4

[0066] The tertiary amine was diluted with a paraffinic mineral oil whenadded to the blend of thermoplastic and elastomer. Blends of PP/BIMSwere prepared by mixing them in a Brabender mixer at a temperature of190° C. and a rotor speed of 60 rpm. The PP pellets were first melted inthe presence of a suitable stabilizer such as Irganox 1076. Theelastomer followed by the oil-diluted Armeen DM16D was subsequentlyadded. At the end, a metal oxide, e.g., MgO, was also added in the blendto act as an acid acceptor. Several ILA compositions with athermoplastic/elastomer blend ratio of 40/60 are shown in Table 8(numbers expressed in parts by weight). For inventive composition (b),an exact stoichiometric match in the bromine and amine groups wasadopted, while in inventive compositions (a) and (c) more and less aminethan bromine groups, respectively, are present.

[0067] Each ILA composition of Table 8 was compression-molded at 190°for 15 minutes to make pads of thickness about 0.08 inch. Tensilestress-strain measurements were performed on these molded pads (storedunder ambient conditions for 48 hours prior to tests). Micro-dumbbellspecimens (ASTM D1708) were used (test temperature 25° C.; Instroncross-head speed 2 inch/min). As shown in Table 8 the incorporation ofionic associations in the PP/BIMS/oil blends (inventive examples (a) to(c) containing 10 phr oil). increases the strain at break, the maximumstress near the break point, and the tensile toughness (defined as thearea under the stress-strain curve) significantly compared to thecontrol example.

Example 5

[0068] Other ILA compositions with a thermoplastic/elastomer blend ratioof 30/70 are shown in Table 9 (numbers expressed in parts by weight).For inventive compositions (d) and (e) with 10 phr and 20 phr oilrespectively, an exact stoichiometric match in the bromine and aminegroups was adopted. Here, again it can be noted that incorporation ofionic associations in the PP/BIMS/oil blend (10 phr or 20 phr oil)increases the strain at break, the maximum stress near the break point,and the tensile toughness significantly compared to the controls.

[0069] In Table 10, ILA compositions with a thermoplastic/elastomerblend ratio of 30/70 using the higher Mooney BIMS are shown. In thisseries the oil level is also varied. For inventive compositions (f), (g)and (h), an exact stoichiometric match in the bromine and amine groupswas adopted. The results indicate that the incorporation of ionicassociations in the PP/BIMS/oil blend (10, 20 or 30 phr oil) increasesthe maximum stress near the break point and the tensile toughness overthe control examples. At higher oil levels, the strain at break of theblend without ionic associations is higher than the corresponding blendwith ionic associations perhaps due to the higher molecular weight ofBIMS 2.

[0070] While the present invention has been described and illustrated byreference to particular embodiments, those of ordinary skill in the artwill appreciate that the invention lends itself to many differentvariations not illustrated herein. For these reasons, then, referenceshould be made solely to the appended claims for purposes of determiningthe true scope of the present invention.

[0071] All priority documents are herein fully incorporated by referencefor all jurisdictions in which such incorporation is permitted. Further,all documents cited herein, including testing procedures, are hereinfully incorporated by reference for all jurisdictions in which suchincorporation is permitted. TABLE 1 Materials Used DesignationDescription Material BIMS 1 BIMS rubber, Mooney EXXPRO ™ 89-1 viscosityof 35 units, *0.75 ExxonMobil Chemical mol % Br, 5 wt % PMS BIMS 2 BIMSrubber, Mooney EXXPRO ™ 89-4, viscosity of 45 units, *0.75 ExxonMobilChemical mol % Br, 5 wt % PMS BIMS 3 BIMS rubber, Mooney EXXPRO ™ 91-11,viscosity of 65 units, *1.1 ExxonMobil Chemical mol % Br, 5 wt % PMSDM16D Tertiary amine, hexadecyl- Armeen DM16D, Akzo dimethylamine NobelChemical DMHTD Tertiary amine, Armeen DMTD, Akzo hydrogenatedtallowalkyl- Nobel Chemical dimethylamine** M2HT Tertiary amine, ArmeenM2HT, Akzo dihydrogenated Nobel Chemical tallowalkyl-methylamine

[0072] TABLE 2 Viscosity values of BIMS with low and high Mooney values.Shear Rate (l/s) Viscosity* of BIMS 2 Viscosity of BIMS 3 100 1274 1468500 378 383 1000 200 197 1500 136 133

[0073] TABLE 3 Viscosity values of DM16D-niodified BIMS 2 at 220° C. inPa − s. Shear BIMS with BIMS with BIMS with BIMS with Rate 0.1 equiv.0.25 equiv. 0.5 equiv. 1.0 equiv. (l/s) BIMS 2 DM16D DM16D DM16D DM16D100 1274 1673 1649 3304 2910 500 378 426 426 981 916 1000 200 230 239571 505 1500 136 152 171 416 361

[0074] TABLE 4 Thermal stability of DM16D-modified BIMS 2 at 1 s⁻¹ shearrate measured using an oscillatory rheometer. Temperatures were rampedup from 100° C. to 250° C. and down to 100° C. and back up to 250° C. at5° C./min. Viscosity* of BIMS with Viscosity of RIMS with Temperature (°C.) 0.25 equiv. DM16D 1.0 equiv. DM16D 250 (first down) 19770 124000 200(first down) 21089 124000 150 (first down) 26387 117000 100 (first down)39526 111000 150 (second up) 25862 111000 200 (second up) 21600 125000250 (second up) 18909 131000

[0075] TABLE 5 Viscosity values of DMHTD-modified RIMS 2 at 220° C. inPa − s. Shear BIMS with BIMS with BIMS with BIMS with Rate 0.1 equiv.0.25 equiv. 0.5 equiv. 1.0 equiv. (l/s) BIMS 2 DMHTD DMHTD DMHTD DMHTD100 1274 1892 1916 3209 . . .* 500 378 517 594 861 963 1000 200 317 315472 499 1500 136 . . .* 211 312 339

[0076] TABLE 6 Viscosity values of M2HT-modified BIMS 2 at 220° C. in Pa− s. Shear BIMS with BIMS with BIMS with BIMS with Rate 0.1 equiv. 0.25equiv. 0.5 equiv. 1.0 equiv. (l/s) BIMS 2 M2HT M2HT M2HT M2HT 100 1274N/C* 1997 2372 2227 500 378 N/C 496 645 679 1000 200 N/C 263 368 3881500 136 N/C 182 276 275

[0077] TABLE 7 BIMS dispersion size Blend Dispersion Size (micron)Control 2.08 Modified BIMS 1.42

[0078] TABLE 8 Copolymer blend with Polypropylene Component/property(parts by weight) Control (a) (b) (c) PP4772 18 18 18 18 BIMS 1 27 27 2727 Armeen DM16D — 1.5 1.0 0.5 Oil 4.5 4.5 4.5 4.5 Irganox 1076 0.09 0.090.09 0.09 MgO (Maglite D) 0.135 0.135 0.135 0.135 100% Modulus, psi 570950 830 720 200% Modulus, psi — 1170 1100 960 Strain at break, % 130 500470 410 Max. Stress near Break, psi 580 1800 1600 1400 TensileToughness, psi 670 6240 2440 1850

[0079] TABLE 9 Copolymer blend with Polypropylene Component/property(parts by weight) Control Control (d) (e) PP 4772 13.5 13.5 13.5 13.5BIMS 1 31.5 31.5 31.5 31.5 Armeen DM16D — — 1.16 1.16 Oil 4.5 9.0 4.59.0 Irganox 1076 0.09 0.09 0.09 0.09 MgO (Maglite D) 0.135 0.135 0.1350.135 100% Modulus, psi 100 75 440 280 200% Modulus, psi 70 24 660 460Strain at Break, % 570 350 640 680 Max. Stress near Break, psi 8 3 13801100 Tensile Toughness, psi 270 120 5470 4430

[0080] TABLE 10 Copolymer blend with Polypropylene Component/property(parts by weight) Control Control Control (f) (g) (e) PP 4772 13.5 13.513.5 13.5 13.5 13.5 BIMS 2 31.5 31.5 31.5 31.5 31.5 31.5 Armeen DM16D —— — 1.16 1.16 1.16 Oil 4.5 9.0 13.5 4.5 9.0 13.5 Irganox 1076 0.09 0.090.09 0.09 0.09 0.09 MgO (Maglite D) 0.135 0.135 0.135 0.135 0.135 0.135100% Modulus, psi 180 130 36 550 320 440 200% Modulus, psi 160 100 26830 510 630 Strain at Break, % 650 920 1280 710 710 600 Max. Stress near35 3 0.2 1900 1230 1200 Break, psi Tensile Toughness, psi 730 450 1108100 5200 4500

We claim:
 1. A thermoplastic composition comprising at least oneisoolefin copolymer comprising a halomethylstyrene derived unit mixedwith at least one hindered amine or phosphine compound having therespective structure R₁ R₂ R₃ N or R₁ R₂ R₃ P wherein R₁ is H or C₁ toC₆ alkyl, R₂ is C₁ to C₃₀ alkyl and R₃ is C₄ to C₃₀ alkyl and furtherwherein R₃ is a higher alkyl than R₁; and a thermoplastic.
 2. Thecomposition of claim 1, wherein the isoolefin copolymer and the amine orphosphine are mixed prior to addition of the thermoplastic, the mixingaccomplished at a temperature above the melting point of said hinderedamine or phosphine compound.
 3. The composition of claim 1, wherein thethermoplastic comprises from 10 to 90 wt % of the composition.
 4. Thecomposition of claim 1, wherein the thermoplastic is selected frompolyolefins, polyamides, polyimides, polyesters, polycarbonates,polysulfones, polylactones, polyacetals, acrylonitrile/butadiene/styrenecopolymer resins, polyphenylene oxides, ethylene-carbon monoxidecopolymers, polyphenylene sulfides, polystyrene, styrene/acrylonitrilecopolymer resins, styrene/maleic anhydride copolymer resins, aromaticpolyketones and mixtures thereof.
 5. The composition of claim 1, whereincuratives are substantially absent.
 6. The composition of claim 1,wherein R₃ is C₁₀ to C₂₀ alkyl.
 7. The composition of claim 1, whereinsaid hindered compound is a tertiary amine and wherein R₃ is C₁₀ to C₂₀alkyl.
 8. The composition of claim 3, wherein R₁ and R₂ are each methyl.9. The composition of claim 1, containing from 0.05 to 2 moles of amineor phosphine per halogen.
 10. The composition of claim 1, wherein theisoolefin copolymer is a halogenatedpoly(isobutylene-co-p-methylstyrene).
 11. The composition of claim 7,wherein the vulcanized thermoplastic composition has a strain at breakvalue of greater than 200%.
 12. The composition of claim 7, wherein thevulcanized thermoplastic composition has a tensile toughness of greaterthan 1000 psi.
 13. A process for preparing a thermoplastic compositioncomprising mixing: at least one isoolefin copolymer comprising ahalomethylstyrene derived unit: at least one hindered amine or phosphinecompound having the respective structure R₁ R₂ R₃ N or R₁ R₂ R₃ Pwherein R₁ is H or C₁ to C₆ alkyl, R₂ is C₁ to C₃₀ alkyl, and R₃ is C₄to C₃₀ alkyl and further wherein R₃ is a higher alkyl than R₁,; and athermoplastic, and recovering a thermoplastic composition.
 14. Theprocess of claim 13, wherein the mixing takes place at a temperature offrom 150° C. to 240° C.
 15. The process of claim 13, wherein thethermoplastic comprises from 10 to 90 wt % of the composition.
 16. Theprocess of claim 13, wherein the thermoplastic is selected frompolyolefins, polyamides, polyimides, polyesters, polycarbonates,polysulfones, polylactones, polyacetals, acrylonitrile/butadiene/styrenecopolymer resins, polyphenylene oxides, ethylene-carbon monoxidecopolymers, polyphenylene sulfides, polystyrene, styrene/acrylonitrilecopolymer resins, styrene/maleic anhydride copolymer resins, aromaticpolyketones and mixtures thereof.
 17. The process of claim 13, whereinsaid thermoplastic polymer is polypropylene or nylon.
 18. The process ofclaim 13, wherein R₃ is C₁₀ to C₂₀ alkyl.
 19. The process of claim 13,wherein curatives are substantially absent.
 20. The process of claim 13,wherein R₁ and R₂ are each methyl.
 21. The process of claim 13, whereinsaid copolymer contains from 0.05 to 2 moles of amine or phosphine perhalogen.
 22. The process of claim 13, wherein a solvent is substantiallyabsent during mixing.
 23. The process of claim 13, wherein the isoolefincopolymer is a halogenated poly(isobutylene-co-p-methylstyrene).
 24. Acomposition produced by the process of claim
 13. 25. A process forpreparing a thermoplastic composition comprising first mixing at leastone isoolefin copolymer comprising a halomethylstyrene derived unit: atleast one hindered amine or phosphine compound having the respectivestructure R₁ R₂ R₃ N or R₁ R₂ R₃ P wherein R₁ is H or C₁ to C₆ alkyl, R₂is C₁ to C₃₀ alkyl, and R₃ is C₄ to C₃₀ alkyl and further wherein R₃ isa higher alkyl than R₁,; recovering an amine or phosphine/copolymercomposition; mixing the amine or phosphine/copolymer composition and athermoplastic; and recovering a thermoplastic composition.
 26. Theprocess of claim 25, wherein the mixing is accomplished at a temperatureabove the melting point of said hindered amine or phosphine compound.27. The process of claim 25, wherein the thermoplastic comprises from 10to 90 wt % of the composition.
 28. The process of claim 25, wherein thethermoplastic is selected from polyolefins, polyamides, polyimides,polyesters, polycarbonates, polysulfones, polylactones, polyacetals,acrylonitrile/butadiene/styrene copolymer resins, polyphenylene oxides,ethylene-carbon monoxide copolymers, polyphenylene sulfides,polystyrene, styrene/acrylonitrile copolymer resins, styrene/maleicanhydride copolymer resins, aromatic polyketones and mixtures thereof.29. The process of claim 25, wherein said thermoplastic polymer ispolypropylene or nylon.
 30. The composition of claim 25, wherein theviscosity value of the amine or phosphine/copolymer composition is from1300 to 6000 Pa·s at 220° C. and 100 1/s shear rate.
 31. The compositionof claim 25, wherein the viscosity value of the amine orphosphine/copolymer composition is greater than 200 at 220° C. and 10001/s shear rate.
 32. The process of claim 25, wherein a solvent issubstantially absent during mixing.
 33. The process of claim 25, whereincuratives are substantially absent.